The present invention relates to gas turbine technology and, more particularly, to a modified blade and/or disk dovetail designed to divert the blade load path around a stress concentrating feature in the disk on which the blade is mounted and/or a stress concentrating feature in the blade itself.
Certain gas turbine disks include a plurality of circumferentially spaced dovetails about the outer periphery of the disk defining dovetail slots therebetween. Each of the dovetail slots receives in an axial direction a blade formed with an airfoil portion and a blade dovetail having a shape complementary to the dovetail slots.
The blades may be cooled by air entering through a cooling slot in the disk and through grooves or slots formed in the dovetail portions of the blades Typically, the cooling slot extends circumferentially 360° through the alternating dovetails and dovetail slots.
It has been found that interface locations between the blade dovetails and the dovetail slots are potentially life-limiting locations due to overhanging blade loads and stress concentrating geometry. In the past, dovetail backcuts have been used in certain turbine engines to relieve stresses. These backcuts, however, were minor in nature and were unrelated to the problem addressed here. Moreover, the locations and removed material amounts were not optimized to maximize a balance between stress reduction on the disk, stress reduction on the blades, and a useful life of the blades.